docs: def get_metadata(self, filename):
          '''Fetch all availabe metadata'''
          obj = self.bucket.Object(filename)
          checksum = 'md5:{0}'.format(obj.e_tag[1:-1])
          mime = obj.content_type.split(';', 1)[0] if obj.content_type else None
          return {
              'checksum': checksum,
              'size': obj.content_length,
              'mime': mime,
              'modified': obj.last_modified,
          }